The previous/next links can slow down the listing details pages noticably, and also increase your server load. If you notice slow pages or high server load, it's best to try switching this off to see if it helps.
If most or all of your listings have images, you might want to link thumbnails of the next and previous. You can do that with this template code, which is already included in the WSN Gallery listing details template and can be added to the other scripts:
<IF {PREVIOUSEXISTS} or {NEXTEXISTS}>
<table>
<tr>
<IF {PREVIOUSEXISTS}>
<td><a href="{PREVIOUSURL}">◄</a></td>
<td><a href="{PREVIOUSURL}"><img src="thumbnail.php?id={PREVIOUSID}&thumbwidth=50&thumbheight=50&fixedsize=1" class="navigationimage" ></a></td>
</IF>
<td><img src="thumbnail.php?id={LINKID}&thumbwidth=50&thumbheight=50&fixedsize=1" class="navigationimage" style="opacity: .5;" ></td>
<IF {NEXTEXISTS}>
<td><a href="{NEXTURL}"><img src="thumbnail.php?id={NEXTID}&thumbwidth=50&thumbheight=50&fixedsize=1" class="navigationimage" ></a></td>
<td><a href="{NEXTURL}">►</a></td>
</IF>
</tr>
</table>
</IF>
<table>
<tr>
<IF {PREVIOUSEXISTS}>
<td><a href="{PREVIOUSURL}">◄</a></td>
<td><a href="{PREVIOUSURL}"><img src="thumbnail.php?id={PREVIOUSID}&thumbwidth=50&thumbheight=50&fixedsize=1" class="navigationimage" ></a></td>
</IF>
<td><img src="thumbnail.php?id={LINKID}&thumbwidth=50&thumbheight=50&fixedsize=1" class="navigationimage" style="opacity: .5;" ></td>
<IF {NEXTEXISTS}>
<td><a href="{NEXTURL}"><img src="thumbnail.php?id={NEXTID}&thumbwidth=50&thumbheight=50&fixedsize=1" class="navigationimage" ></a></td>
<td><a href="{NEXTURL}">►</a></td>
</IF>
</tr>
</table>
</IF>